I think your female is just stronger, maybe larger, maybe not.
I think it is not the gunk that directly lead to ammonia but it probably blocked up the filter bacteria area plus the flow rate dropped due to the clogging and this lead to less O2 for the bacteria. Bacteria always die off and leave brown gunk, you need to flush it out regularly with old tank water.
I think canisters should always be run with another so you can alternate cleaning. A sump and a canister for back up is way better.
As the rays grow they produce more and more waste so your filters need to grow too. You may consider a faster flowing media for the larger filter. If you have room above the tank then the fx5 could return up past the tank and back down through a pond filter above, not nice looking but might do the job.
If you ever see a large spike like that then do a 40% or more and do another the next day.
The new filter would not have caused this.